Process for the production of alkali metal peroxide



Nov. 8, 1960 PROCESS FOR THE PRODUCTION OF ALKALI METAL PEROXIDE.

Filed July 29. 1957 Qu/vA/a MAu/a/r'z ,QAFA 515:0 QRNHJELM Arron/5K I R.M. R. ORNHJELM 2,959,468

o l t i ted States Patent O ce I Patented Nov. 8, 1960 serve ascrystal-nuclei for production of a coarse grain 2,959,468 product Theinvention also comprises a device for the execu- PROCESSFORTHEPRODUCTION F ALKALI tion of the foregoing process, which device ismainly METAL PEROXIDE 5 characterized by a preferably vertical reactortower with Rnnar Mauritz Rafaelsson Ornhjelm, Kuusankoski, Findevices atits lower end for continuous introduction of land, assignor to KyminOsakeyhtio-Kymmene Aktiehydrazobenzene from the reduction phase of adevice bolag, Kuusankoski, Finland, a company of Finland known per sefor production of alkali peroxide with a suitable autoxidable organicmixture as initial material Flled July 1957 674943 as well as devicesfor introduction of oxygen to the hy- Claims priority, applicationSweden July 30, 1956 drazobenzene in as fine and even distribution aspossible in close connection to its lace of introduction in t e 4Clauns. (c1. 23-184) reactiomwwen p l A device in accordance with theinvention is sche- This invention relates to a process in the productionmatically shown as an example on the enclosed drawing, of alkaliperoxide by oxidation of autoxidative organic which shows only the partbelonging to the oxidation substances, like hydrazobenzene in solution,with the aid phase of the process of production, while leaving out theof oxygen in presence of water and alkali, separation of reduction phaseand other parts nonessential in relation the alkali peroxide formed andreduction of the oxidized to the invention. organic substance as asuspension in the reaction com- On the drawing 1 designates a vertical,longish oxidapound with aid of alkali amalgam to be led back into tiontower or tube, to which the refrigerated hydrazocirculation. benzenesolution with necessary percentage of alkali is In the processeshitherto known, the crystallisation introduced from the reduction phaseby means of a pump of the alkali peroxide in the oxidation phase, hascaused 2 at the inlet 3. 4 on the drawing marks the inlet for very bigdifliculties, as the precipitating crystals stick to introduction ofoxygen near the bottom of the tower but the walls of the aggregate andblock pipings and nozzles, preferably somewhat above the inlet 3 forhydrazobenin addition to which the alkali peroxide of very fine grainzene solution. The oxygen inlet is equipped with an oxyconsistenceproduced by previous processes contains gen atomiser 5 shown onlyschematically. Both the great amounts of solvent medium andautocatalyzer liquid and the gas thus flow in the same direction fromwhich is strongly colouring and negatively affects the perthe bottom tothe top and the velocity of the flow is manence of the peroxide and itspossibilities of use, at chosen so, that a sedimentation of solidmaterial in the the same time as the expenses increase due to the lossesreaction-tower is avoided. According to the drawing the f lv t di d thecostly autoeatalyzer, The crystals begin to form at a height 6 after thereaction foregoing disadvantages, especially the difiiculties in congreached a Certain stage- For instance r g z nection with the operation,are avoided according to this in alcoholic Solution it has been found,that the Velocity invention, which is characterized thereby, that thehyof sedimentation is approx. 0.2"/sec. naturally dependdrazobenzenesolution is introduced at one end, and g S e hat on he Size of thecrystals and the concenbrought to flow with such a continuous speedthrough tration of the solution. In order to avoid sedimentation aclosed, at its other end furnished with an outlet, longand to achievethat the crystals are carried away with ish, preferably pipe-likereaction-path, under introducing the how of q Velocity of the how hasnaturally f xygen near th i l t, th t d t th velocity f th to exceed thevelocity of sedimentation to a suflicient reaction as well as the courseof the flow and the exten- Usually a Velocity of flow 1W0 times t of thign of the reaction-path, depending on the supplied resedimentationought t0 be sufiicient, but has naturally t0 action components, adesired amount of hydrazobenzene be determined Separately in each caseand is easily reguwill be oxidized whereas at the same timeprecipitating lated y the P p 2 and the n od ced oxygen. Recrystals ofalkali peroxide are carried away with the flow gardillg the latter o esave however to be avoided. i f of a Suspension, t b brgught i h formingAt the upper end of the reaction tower the reaction mixsediments, to theopposite end of the reactor-path, where tufe containing Peroxidecrystals is taken out thfough an it is taken out together with theazobenzene solution in a Outlet The Peroxide is separated and e a ti nmanner known per se, and separated therefrom outside liquid is PalflyCompletely led back i t Cir ulation as the reactor-path, at whichinstance the azobenzene soludescribed above the feduetol 11 Sh Wntionrecovered from the alkali peroxide is led back into Uhreeeted Oxygen gasmay naturally e co ered and h i l i h h a reducton after the outlet 7 asediment-bowl 8 may suitably be in- If the hydrazobenzene is notcompletely oxidized, in Stalled in Which, in certain cases, aPest-Oxidation y which case it is removed together with the azobenzeneat take Place and from Which the Peroxide th n is taken the outlet endof the reactor-path, the mixture of these to a centrifuge From thecentrifuge the P 21 may, ft eventual separation f h lk li peroxide,benzene solution is transferred to the reduction phase. a large extentbe led back to the oxidation phase, where- Naturally the Outlet-end 0the re ctiton tower should as the remainder is transfer-red to thereduction phase, at he built With e Cone-like decreasing die-meter,whereby the same time correspondingly decreasing the quantity of OutletIn{11y be connected to this end in Such a y, hydrazobenzene solutiontransferred from the reduction that at least larger gatherings of gas,Which ay cause phase to the oxidation phase. When applying such aexplosions, are avoidedprocess the extension of the reaction-path in theoxida- By choosing the right material for the reaction-tower tion phasecan be decreased, which is also achieved by or the lining thereof, thetendency of the alkali peroxide having two or more reactor-paths coupledin series, Crystals to Stick to the Walls can to a great extent e wherebetween eventually is made a separation of the eliminatedalkali peroxideobtained. It is in certain cases advan- What 1 Claim is tageous to leadback the crystal substance or at least part 1. In a process for theproduction of alkali metal perof it, taken out already before the finaloutlet, to the oxide by oxidizing a solution of an auto oxidativeorganic reaction-path together with the incompletely oxidizedreaction-mixture, so that the crystals thus introduced substance havingat least two relatively easily split hydrogen atoms in the molecule withthe aid of oxygen in the presence of water and alkali metal amalgam,separating alkali metal peroxide formed as a suspension in the reactionmixture and reducing the oxidized organic substance with the aid of saidalkali metal amalgam and recycling said reduced organic substance, theimprovement which comprises introducing said reduced organic substancein solution into the lower end of a vertical, elongated, transverselyrestricted reaction zone, causing said substances to flow continuouslyupwardly through said zone by introducing oxygen near the inlet endthereof, controlling the velocity of the reaction, the velocity of theflow, the extension of the reaction zone and the supply of thecomponents so as to oxidize a desired amount of the auto oxidativeorganic substances and precipitate crystals of alkali metal peroxide,said crystals flowing upwardly in the form of a suspension, at avelocity sufiicient to prevent sedimentation, to the opposite end ofsaid reaction zone, removing said crystals together with said solutionof oxidized organic substance and separating the crystals from saidsolution outside the reaction zone, reducing said solution separatedfrom the alkali metal peroxide and leading said reduced organicsubstance back into said reaction zone.

References Cited in the file of this patent UNITED STATES PATENTS2,083,691 Cunningham June 15, 1937 2,158,523 Pfleiderer May 16, 19392,215,856 Pfleiderer Sept. 24, 1940 2,257,533 Reich Sept. 30, 19412,702,741 Robertson Feb. 22, 1955 2,726,935 Canfield et a1 Dec. 13, 19552,737,440 Roberts et a1. Mar. 6, 1956 2,797,151 Schnur et al. June 25,1957

1. IN A PROCESS FOR THE PRODUCTION OF ALKALI METAL PEROXIDE BY OXIDAZINGA SOLUTION OF AN AUTO OXIDATIVE ORGANIC SUBSTANCE HAVING AT LEAST TWORELATIVELY EASILY SPLIT HYDROGEN ATOMS IN THE MOLECULE WITH THE AID OFOXYGEN IN THE PRESENCE OF WATER AND ALKALI METAL AMALGAM, SEPARATINGALKALI METAL PEROXIDE FORMED AS A SUSPENSION IN THE REACTION MIXTURE ANDREDUCING THE OXIDIZED ORGANIC SUBSTANCE WITH THE AID OF SAID ALKALIMETAL AMALGAM AND RECYCLING SAID REDUCED ORGANIC SUBSTANCE, THEIMPROVEMENT WHICH COMPRISES INTRODUCING SAID REDUCED ORGANIC SUBSTANCEIN SOLUTION INTO THE LOWER END OF A VERTICAL, ELONGATED, TRANSVERSELYRESTRICTED REACTION ZONE, CAUSING SAID SUBSTANCES TO FLOW CONTINUOUSLYUPWARDLY THROUGH SAID ZONE BY INTRODUCING OXYGEN NEAR THE INLET ENDTHEREOF, CONTROLLING